glued(${\it es}$; $B$; $f$; ${\it Ia}$; ${\it Ib}$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$$\exists$$g$:es{-}E{-}interface(${\it es}$;${\it Ib}$)$\rightarrow$es{-}E(${\it es}$). glues(${\it es}$; $B$; $g$; $f$; ${\it Ia}$; ${\it Ib}$)